Network interface device and method having passive operation mode and noise management

ABSTRACT

A system, method and device provide passive operation mode and noise management. The system, in one embodiment, includes power loss bypass and upstream noise management.

PRIORITY CLAIM

This application is a non-provisional of, and claims the benefit andpriority of, U.S. Provisional Patent Application Ser. No. 61/714,930,filed on Oct. 17, 2012.

INCORPORATION BY REFERENCE

The entire contents of the following applications are herebyincorporated by reference: (a) U.S. Provisional Patent Application Ser.No. 61/714,930, filed on Oct. 17, 2012; (b) U.S. patent application Ser.No. 13/969,064, filed on Aug. 16, 2013; (c) U.S. patent application Ser.No. 13/669,805, filed on Nov. 6, 2012; and (d) U.S. Provisional PatentApplication Ser. No. 61/559,598, filed on Nov. 14, 2011.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to the following commonly-owned, co-pendingpatent applications: (a) U.S. patent application Ser. No. 13/969,064,filed on Aug. 16, 2013; (b) U.S. patent application Ser. No. 13/669,805,filed on Nov. 6, 2012; and (c) U.S. Provisional Patent Application Ser.No. 61/559,598, filed on Nov. 14, 2011.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains or maycontain material which is subject to copyright protection. The copyrightowner has no objection to the photocopy reproduction by anyone of thepatent document or the patent disclosure in exactly the form it appearsin the Patent and Trademark Office patent file or records, but otherwisereserves all copyrights whatsoever.

BACKGROUND

Cable television (CATV) networks supply high frequency “downstream”signals from a main signal distribution facility, known as a “headend,”through the CATV network infrastructure, to the homes and offices ofsubscribers The downstream signals are supplied to the subscriberequipment, such as television sets, telephone sets and computers, toenable them to operate.

In addition, most CATV networks also transmit “upstream” signals fromthe subscriber equipment back to the headend of the CATV network. Forexample, a set top box enables the subscriber to select a TV program fordisplay on the television set by transmitting the program selection tothe CATV provider. Upstream signals are sent from the set top box to theheadend signal-delivering equipment. This equipment responds bytransmitting the selected downstream signal to the subscriber. Asanother example, two-way communication occurs when using a personalcomputer connected through the CATV infrastructure to the publicInternet. As a further example, voice over Internet protocol (VOIP)telephone enabled devices use the CATV infrastructure and the publicInternet as the medium for transmitting two-way telephone conversations.Such two-way signal transmission (upstream and downstream) is thereforean important feature for modern CATV networks.

Passive-active network interface devices have been developed to provideboth passive and active, i.e. amplified, signals at the subscriberpremises for the two different types of subscriber devices which operatefrom passive and active signals. Such passive-active network interfacedevices include a signal splitter which essentially divides or branchesthe incoming, or “downstream,” signals from the cable network intopassive and active branches. The passive branch downstream signals areconducted through a passive branch of the network interface devicewithout amplification or modification and applied to those subscriberdevices which require passive signals for operation, such as, forexample, a voice modem for a telephone set. The active branch downstreamsignals are conducted to an active signal conditioner, such as anamplifier, of an active branch of the network interface device. Theactive signal conditioner amplifies the strength of the signals ormodifies some characteristic of the signals before the amplified, orconditioned, signals are delivered to one or more subscriber devices.The amplified signals are applied to those subscriber devices thatbenefit from the amplified signals, such as a television sets andcomputers.

The known passive-active interface devices have several disadvantages.They include electromechanical, moving parts. The moving parts can causehigher instances of failure or require undesirable levels of repair andmaintenance. Also, the complexity of the known passive-active interfacedevices is associated with a relatively high manufacturing cost which,in turn, leads to a higher price passed along to the users of cablenetwork services.

The high-frequency signals conducted through the cable network aresusceptible to distortion from a number of sources. It is for thisreason that coaxial cables are widely used to shield the high-frequencysignals from degrading influences of the ambient environment. Onerequirement for maintaining high-quality signal conduction in a coaxialcable is properly terminating the coaxial cable. An improper terminationcauses reflections of the incident signals back into the transmissionpath. The reflections cause degradation of the desired incident signalsreceived by the subscriber. The degradations are exemplified byamplitude ripple, group delay ripple, latency, and other similar effectswhich distort or reduce the incident signals. The signal reflectionscause the subscriber to experience a degraded quality of service, or insome cases the level of degradation may prevent the subscriber fromreceiving meaningful service.

Therefore, there is a need to overcome, or otherwise lessen the effectsof, the disadvantages and shortcomings described above.

SUMMARY

The network interface device (NID), in one embodiment, is operable toconnect subscriber equipment to a CATV network over which downstreamsignals in a first frequency band from a headend of the CATV network,are transmitted to the subscriber equipment. Valid upstream signals in asecond different frequency band are transmitted from the subscriberequipment to the headend. The network interface device has an upstreamnoise mitigation circuit which mitigates ingress noise into the CATVnetwork in the second frequency band. The network interface device alsohas a bypass circuit for lifeline preservation, including an upstreamfilter which filters upstream signals before delivery to the CATVnetwork, and a bypass circuit is connected to the noise mitigationcircuit. The bypass circuit includes a lifeline signal path, and thebypass circuit includes a relay. The relay switches the signal pathbetween the noise mitigation circuit and the lifeline path. The relayswitches to the lifeline path during a power-off condition.

In one embodiment, the NID includes a signal splitter that is operableto separate a downstream signal into a passive branch signal and/or anactive branch signal. An active branch circuit transmits the activebranch signal to an active subscriber device. An active branch circuitnoise manager detects an upstream signal transmitted from the least oneactive subscriber device and establishes a signal path for the detectedupstream signal through the active branch circuit. The NID also includesa passive branch circuit to transmit the passive branch signal to apassive subscriber device.

In another embodiment, an NID includes a signal splitter that separatesa downstream signal into a passive branch signal and/or an active branchsignal. An active branch circuit transmits the active branch signalto/from an active subscriber device. An active branch circuit noisemanager detects an upstream signal transmitted from the least one activesubscriber device and establishes a signal path for the detectedupstream signal through the active branch circuit. A passive branchcircuit transmits the passive branch signal to/from passive subscriberdevice. The NID also includes a switch (or bypass relay) operable tocontrol transmission of signals to/from the active subscriber device.

In a further embodiment, an NID includes an input port used tocommunicate with a CATV network. A signal splitter separates adownstream signal into a passive branch signal and/or an active branchsignal. The NID includes a gas tube surge protector located on aconnection between the input port and the signal splitter. An activebranch circuit transmits the active branch signal to/from an activesubscriber device. An active branch circuit noise manager (or noisemitigation circuit) detects an upstream signal transmitted from theleast one active subscriber device and establishes a signal path for thedetected upstream signal through the active branch circuit. A passivebranch circuit transmits the passive branch signal to/from passivesubscriber device. A bypass circuit bypasses the signal path through theactive branch circuit during a power-off condition.

In another embodiment, a noise mitigation circuit detects an upstreamsignal transmitted from an active subscriber device and establishes asignal path for the detected upstream signal through the active branchcircuit.

Additional features and advantages of the present disclosure aredescribed in, and will be apparent from, the following Brief Descriptionof the Drawings and Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a network interface device whichincorporates an embodiment and a block diagram of subscriber equipmentshown connected to a CATV network through the network interface devicelocated at a subscriber's premises.

FIG. 2 is a block diagram of portions of a typical CATV network, withmultiple network interface devices of the type shown in FIG. 1 connectedby drop cables to cable taps, as well as other aspects of the CATVnetwork.

FIG. 3 is a block diagram of basic functional components within thenetwork interface device shown in FIG. 1.

FIGS. 4, 5 and 6 contain multiple waveform diagrams on a common timeaxis, illustrating the functional features of an upstream noisemitigation circuit of the network interface device shown in FIG. 3.

FIG. 7 is a block diagram of basic functional components of an upstreamnoise mitigation circuit which is an alternative to that shown in FIG.3.

FIGS. 8, 9 and 10 contain multiple waveform diagrams on a common timeaxis, illustrating the functional features of the upstream noisemitigation circuit shown in FIG. 7.

FIG. 11 depicts a block diagram of an embodiment of a power loss bypasscircuit.

FIG. 12 depicts a circuit layout of the power loss bypass circuit shownin FIG. 11.

FIG. 13 depicts a block diagram of an embodiment of basic functionalcomponents within a network interface device.

FIG. 14 depicts a block diagram of another embodiment of basicfunctional components within a network interface device.

DETAILED DESCRIPTION

Part I

The infrastructure of a CATV network may include interconnected coaxialcables, signal splitters and combiners, repeating amplifiers, filters,trunk lines, cable taps, drop lines and other signal-conducting devices.The CATV network may be connected to a subscriber's home via a networkinterface device. This enables the subscriber's devices to communicatewith the CATV network.

An NID or network interface device 10, which incorporates an embodiment,is shown in FIG. 1. The network interface device 10 includes a housing12 which encloses internal electronic circuit components (such as shownin FIGS. 3 and 7). A mounting flange 14 surrounds the housing 12, andholes 16 in the flange 14 allow attachment of the interface device 10 toa support structure at a subscriber's premises 18.

The interface device 10 is connected to a CATV network 20, which isshown in a typical topology in FIG. 2. Downstream signals 22 originatefrom programming sources at a headend 24 of the CATV network 20, and areconducted to the interface device 10 in a sequential path through a maintrunk cable 26, a signal splitter/combiner 28, secondary trunk cables30, another signal splitter/combiner 32, distribution cable branches 34,cable taps 36, and drop cables 38. Upstream signals 40 are deliveredfrom the network interface device 10 to the CATV network 20, and areconducted to the headend 24 in a reverse sequential path. Interspersedat appropriate locations within the topology of the CATV network 20 areconventional repeater amplifiers 42, which amplify both the downstreamsignals 22 and the upstream signals 40. Conventional repeater amplifiersmay also be included in the cable taps 36. The cable taps 36 and signalsplitter/combiners 28 and 32 divide a single input downstream signalinto separate downstream signals, and combine multiple upstream signalsinto a single upstream signal.

The network interface device 10 receives the downstream signals 22 fromthe CATV network 20 at a network connection port 44. The downstreamsignals 22 are either passive or active. Passive downstream signals arethose signals which are conducted through the interface device 10without amplification, enhancement, modification or other substantialconditioning. The passive downstream signals are delivered from apassive port 45 to passive subscriber equipment, such as a voice modem46 connected to a telephone set 48, or an embedded multimedia networkinterface device (EMTA, not shown), located at the subscriber premises18. Active downstream signals are those signals which are amplified,filtered, modified, enhanced or otherwise conditioned by power-consumingactive electronic circuit components within the interface device 10. Theconditioned active downstream signals are divided into multiple copiesand delivered from a plurality of active ports 50, 52, 54 and 56 toactive subscriber equipment located at the subscriber premises 18, suchas television (TV) sets and/or data modems 58, 60, 62 and 64. Othersubscriber equipment, such as data processing devices or computers, isconnected to the data modems.

The equipment at the subscriber premises 18 typically generates upstreamsignals 40 (FIG. 2) to the network interface device 10 for delivery tothe CATV network 20. The upstream signals 40 may be either active orpassive upstream signals generated by the subscriber equipment connectedto the active and passive ports 45, 50, 52, 54 and 56. For example, oneor more of the TV sets 58, 60, 62 and 64 may have conventional set topboxes (not shown) associated with them to allow the subscriber/viewer tomake programming and viewing selections. Of course, any computers (notshown) connected to the data modems 58, 60, 62 and 64 typicallycommunicate upstream signals. The telephone set 48 and the voice modem46, or the EMTA (not shown); also generate upstream signals as a part oftheir typical functionality.

Electrical power for the network interface device 10 is supplied from aconventional DC power supply 66 connected to a dedicated power inputport 68. Alternatively, electrical power can be supplied through aconventional power inserter (also shown at 58) that is connected to theport 50. The power inserter allows relatively low voltage DC power to beconducted through the same port 50 that also conducts high-frequencysignals. Use of a conventional power inserter connected to one of theports, e.g. port 50, eliminates the need for a separate dedicated powersupply port 68, or provides an alternative port through which electricalpower can also be applied. The power supply 66 or the power suppliedfrom the port 50 is typically derived from a conventional wall outlet(not shown) within the subscriber premises 18.

The ports 44, 45, 50, 52, 54, 56 and 68 may be conventional femalecoaxial cable connectors which are mechanically connected to the housing12 and which are electrically connected to internal components of theinterface device 10. Coaxial cables from the subscriber equipment andthe drop cables 38 (FIG. 2) are connected to the interface device 10 bymechanically connecting the corresponding mating male coaxial cableconnector (not shown) on these coaxial cables to the female coaxialcable connectors forming the ports 44, 45, 50, 52, 54, 56 and 68.

The internal circuit components of one embodiment of the networkinterface device 10 are shown in FIG. 3. Those internal circuitcomponents include a conventional bi-directional signalsplitter/combiner 70 which separates the input downstream signals 22from the CATV network 20 at the cable port 44 into passive downstreamsignals 72 and active downstream signals 74 within the network interfacedevice 10. The passive downstream signals 72 are conducted directlythrough the passive port 45 to the passive subscriber equipment 46 and48. Passive upstream signals 76 created by the passive subscriberequipment 46 and 48 are conducted through the passive port 45 directlyto the signal splitter/combiner 70 to become upstream signals 40 in theCATV network 20. The direct signal conductivity path for the passivesignals in the network interface device 10 avoids subjecting the passivesignals to potentially adverse influences from electronic componentsthat might fail or malfunction, thereby enhancing the reliability of thepassive communications without increasing the risk of failure. Passivecommunications are intended to be as reliable as possible since they maybe used in emergency and critical circumstances.

The active downstream signals 74 are conducted to active circuitry 78,where the active downstream signals 74 are amplified, filtered,modified, enhanced or otherwise conditioned before delivery through theactive ports 50, 52, 54 and 56 to the subscriber equipment 58, 60, 62and 64. Active upstream signals 80 are created by the subscriberequipment 58, 60, 62 and 64, and also pass through the active circuitry78, where those signals are also conditioned or otherwise modified orenhanced before being combined at the signal splitter/combiner 70 tobecome network upstream signals 40 in the CATV network 20.

The circuit components of the active circuitry 78 receive power from thepower supply 66 connected at port 68 or through the power inserter 58(FIG. 1) connected at port 50. A power-signal divider 82 separates thehigh-frequency active downstream and upstream signals 74 and 80 at port50 from the DC power at port 50. The divider 82 conducts the activesignals 74 and 80 from and to high-frequency signal conductivity pathswithin the active circuitry 78, while simultaneously conducting the DCpower to the active circuitry 78 for use by its electrical powerconsuming components. Electrical power from the dedicated power inputport 68 is also conducted to the power consuming circuit components ofthe active circuitry 78.

The components of the active circuitry 78 which conduct the downstreamactive signals 74 include first and second analog downstream filters 84and 86 that are connected in series by a linear amplifier 88. Thedownstream filters 84 and 86 filter the downstream signals 74 in thedownstream 54-1000 MHz frequency band. The linear amplifier 88amplifies, modifies or enhances the downstream signals 74, and inconjunction with the filters 84 and 86, conditions the downstreamsignals 74. The downstream signals 74 are thereafter connected throughconventional signal splitter/combiners 90, 92 and 94 before thosedownstream signals 74 are delivered through the active ports 50, 52, 54and 56 to the subscriber equipment 58, 60, 62 and 64.

The active upstream signals 80 created by the subscriber equipment 58,60, 62 and 64 are conducted through the active ports 50, 52, 54 and 56to an upstream noise mitigating circuit 100. The upstream noisemitigation circuit 100 transfers valid active upstream signals 80 fromthe subscriber equipment 58, 60, 62 and 64 through the network interfacedevice 10 to the CATV network 20 as upstream signals 40. These functionsare accomplished as described below.

Valid upstream signals from the subscriber equipment 58, 60, 62 and 64are conducted through the signal splitter/combiners 92, 94 and 90 tobecome active upstream signals 80. The upstream signals 80 are appliedto a first upstream signal bandpass filter 102. Because the downstreamsignal filter 86 passes signals only in the 54-1000 MHz band, validupstream signals 80 in the frequency band of 5-42 MHz are blocked by thedownstream signal filter 86 and diverted through the upstream signalfilter 102. The first upstream signal filter 102 preferably passessignals in the valid upstream signal frequency range of 5-42 MHz.Typical ingress noise falls within most intensely within the frequencyrange of 0-15 MHz, so the first upstream filter 102 has the capabilityof removing ingress noise at the low frequencies in the range of 0-5MHz. However, ingress noise in the range of 5-15 MHz will be conductedby the upstream signal filter 102.

To mitigate or prevent ingress noise upstream signals from entering theCATV network 20 from the network interface device 10, ingress noisesignals conducted through the first upstream filter 102 are isolated bya first radio frequency (RF) single pole double throw (SPDT) electronicswitch 104 and terminated to ground through a termination resistor 103.The termination resistor 103 is connected to one terminal of the firstelectronic switch 104. Signals from the first upstream signal filter 102are conducted through a conventional directional coupler 105 to andthrough the switch 104 to the termination resistor 103 while the firstelectronic switch 104 is in a normal position, shown in FIG. 3. Allsignals conducted through the first upstream signal filter 102 areterminated through the termination resistor 103, and are therebyprevented from entering the CATV network 20, while the first switch 104is in its normal position.

The first electronic switch 104 changes to an alternate activatedposition (not shown in FIG. 3) upon the instantaneous power of thesignals conducted through the filter 102 reaching a magnitude indicativeof a valid upstream signal from the subscriber equipment 58, 60, 62 or64. To distinguish relatively low power ingress noise from therelatively higher power of a valid upstream signal, the instantaneousmagnitude of the power of the signals passing through the upstreamfilter 102 is detected and evaluated. The coupler 105 delivers a signal106 which is typically 10 dB lower in power than the signal passingthrough the coupler 105 to the switch 104.

The signal 106 from the coupler 105 is conducted to an input terminal ofa conventional log amplifier detector 108. The log amplifier detector108 operates on an inverse logarithmic basis to convert theinstantaneous magnitude of power of the signal 106 to a DC voltageoutput signal 110. By operating on an inverse logarithmic basis, thetypical decibel power of the input signal 106 is converted into a linearDC voltage output signal 110 whose magnitude is inversely related to theinstantaneous input power. This logarithmic conversion allows the logamplifier detector 108 to function as an instantaneous demodulatingpower detector whose output DC voltage signal is inversely proportionalto the logarithm of the input power. In one embodiment, the log ampdetector 108 includes a commercially available component identified aspart number AD 8319 available from Analog Devices of Norwood Mass., USA.The DC voltage output signal 110 therefore represents the inverse of theinstantaneous power of the upstream signal 80 conducted through thedirectional coupler 105.

The DC voltage output signal 110 from the log amp detector 108 isapplied to a negative input terminal of a comparator 112. A thresholdsignal 114 is applied to the positive input terminal of the comparator112. The threshold signal 114 is derived from a resistor divider networksuch as a potentiometer 116 and a resistor 118 connected in series, orfrom another voltage source. Adjustment of the value of thepotentiometer 116 adjusts the magnitude of the threshold signal 114. Theadjustment of the threshold signal 114 establishes the level where atrigger signal 120 from the comparator 112 switches from a logic lowlevel to a logic high level.

The magnitude of the DC voltage output signal 110 from the log ampdetector 108 is inversely related to the magnitude of the instantaneouspower of the upstream signal represented by signal 106. That is, whenthe magnitude of the upstream signal 106 is relatively large, the DCvoltage output signal 110 from the log amp detector 108 is relativelysmall, and vice versa. Because of this inverse relationship, the DCvoltage output signal 110 is applied to the negative input terminal ofthe comparator 112, and the threshold signal 114 is applied to thepositive input terminal of the comparator 112. Applying the two inputsignals in this manner causes the comparator 112 to supply a logic hightrigger signal 120 whenever the magnitude of the instantaneous power ofthe upstream signal exceeds a predetermined threshold power levelrepresentative of a valid upstream signal. Conversely, when the DCvoltage output signal 110 is greater than the signal 114, the triggersignal 120 from the comparator 112 is at a logic low level. When the DCvoltage output signal 110 is less than the signal 114, the triggersignal 120 from the comparator is at a logic high level. The logic highlevel of the signal 120 therefore represents the condition where theinstantaneous power of the upstream signal exceeds the predeterminedthreshold power level established by the signal 114.

Upon sensing that the instantaneous power content of an upstream signalexceeds the level represented by the predetermined threshold powerlevel, the upstream signal is automatically or immediately transmittedor passed to the CATV network 20 as a network upstream signal 40.Upstream signals which do not meet the threshold power level areconsidered ingress noise. Ingress noise signals are isolated from theCATV network 20 by the switches 104 and 130, while incident upstreamsignals 80 are simultaneously terminated to ground through thetermination resistor 103. The functions of passing upstream signals tothe CATV network and terminating upstream signals to ground areaccomplished in response to the logic level of the trigger signal 120from the comparator 112.

When instantaneous power content of an upstream signal exceeds thethreshold power level, the resulting logic high signal 120 from thecomparator 112 triggers a one-shot timer 122. Simultaneously, the logichigh signal 120 is applied to an input terminal of an OR gate 124. TheOR gate 124 responds by applying a logic high control signal 126 to thecontrol terminals of the first SPDT RF electronic switch 104 and asecond SPDT RF electronic switch 130. The electronic switches 104 and130 normally occupy the positions shown in FIG. 3. Upon the assertion oflogic high control signal 126, the switches 104 and 130 immediatelychange from their normal positions (shown in FIG. 3) to their oppositeactivated positions (not shown). The activated positions of the switches104 and 130 establish a direct connection over conductor 132 between theswitches 104 and 130. Since the electronic switches 104 and 130 switchwith radio frequency speed, the switches 104 and 130 assume theactivated position almost instantaneously in response to the assertionof the control signal 126.

The activated positions of the switches 104 and 130 conduct the upstreamsignal 80 from the first upstream signal filter 102 through theconductor 132 to a second upstream signal filter 134. Both filters 102and 134 suppress frequencies other than those in the frequency band of5-42 MHz. The valid upstream signal flows from the second upstreamfilter 134 through the signal splitter/combiner 70 into the cablenetwork 20 as the network upstream signal 40. Terminating resistors 103and 190 are connected to the filters 102 and 134 when the switches 104and 130 are in their normal positions, and the filters 102 and 134 areconnected together over the conductor 132 when the switches 104 and 130are in their activated positions.

Valid upstream signals are conducted to the CATV network almostinstantaneously when the instantaneous power level of the upstreamsignals exceeds the threshold power level. By responding almostinstantaneously when the threshold power level is exceeded, the chancesare minimized that the information contained in the valid upstreamsignal will be lost, as might be the case if the power of the upstreamsignal had to be integrated over a time period before a determination ofa valid upstream signal could be made on the basis of energy content.Such integration raises the possibility that some of the information ofthe upstream signal will be lost and not transferred upstream. Incontrast, no integration of the power of the upstream signal over aselected time period is required in the upstream noise mitigationcircuit 100. By almost instantaneously transmitting upstream signalswhich have a power content that exceeds the predetermined thresholdpower level, the integrity of the information contained in the upstreamsignal is better preserved.

Once the switches 104 and 130 have been moved to the activated positionwhich directly connects the first and second upstream signal filters 102and 134 through the conductor 132, the switches 104 and 130 aremaintained in this activated position for a time determined by theone-shot timer 122. When triggered by the logic high signal 120, theone-shot timer 122 immediately supplies a logic high output signal 136to the OR gate 124. Either logic high signal 120 or 136 causes the ORgate 124 to supply the logic high control signal 126. If the power levelof the upstream signal falls below the level of the threshold signal114, the signal 120 immediately assumes a logic low level. However, theone-shot timer 122 will continue to deliver the logic high output signal136 for the time duration of its internal time constant.

The internal time constant of the one-shot timer 122 is equal to theamount of time to transmit a single valid upstream signal packet of themaximum time duration permitted by the signaling protocol, plus a slightadditional amount of time to account for inherent tolerances in thecomponents and the timing of the one-shot timer 122. In this manner, theone-shot timer 122 ensures that the switches 104 and 130 assume theiractivated positions for a long enough time to conduct all single validupstream signals, including a maximum-length valid upstream signal orpacket.

The situation just described is illustrated by the waveform diagramsshown in FIG. 4, taken in connection with FIG. 3. The signal 106represents a single valid upstream packet of the permitted maximum timeduration whose detection by the log amp detector 108 produces the logichigh trigger signal 120. The signal 120 assumes the logic high level attime point 138, triggering the one-shot timer 122 and causing the outputsignal 136 to be asserted at the same time point 138. The control signal126 from the OR gate 124 immediately assumes a logic high level at timepoint 138. The electronic switches 104 and 130 assume their activatedpositions for the duration of the logic high control signal 126. At timepoint 139, the maximum time duration of a single valid upstream packetor signal ends, and the instantaneous power represented by that signalfalls below the threshold power level represented by the thresholdsignal 114. The signal 120 assumes a logic low level. Since the timeconstant of one-shot timer 122 is established to slightly exceed themaximum time duration of a single valid upstream packet or signal, thelogic high signal 136 will continue to time point 140. When the signal136 assumes a logic low level after the one-shot timer 122 times out attime point 140, the control signal 126 from the OR gate 124simultaneously assumes a logic low level. As a result, the controlsignal 126 is longer in duration than signal 120. When the controlsignal 126 assumes the low logic level at time point 140, the electronicswitches 104 and 130 assume their normal positions to conduct anyupstream signals to the termination resistor 103, thereby terminatingthose signals to ground and preventing the further upstream signals fromreaching the CATV network.

For multiple valid upstream signal packets which are consecutivelytransmitted without a substantial time interval separating the multiplesequential upstream packets, the one-shot timer 122 will time out beforethe valid upstream signal transmission terminates. However, thecontinuous instantaneous power of the multiple sequential valid upstreamsignal packets will continue to exceed the threshold power level for theduration of the multiple sequential signal packets, thereby causing thecomparator 112 to continue to assert the logic high trigger signal 120to the OR gate 124 for the duration of the multiple sequential signalpackets. The continued application of the logic high signal 120 causesthe OR gate 124 to assert the logic high control signal 126 beyond thetime when the one-shot timer 122 times out. The two upstream signalfilters 102 and 134 remain connected by the switches 104 and 130 intheir activated positions, and thereby conduct the multiple sequentialupstream signal packets to assure that the full information representedby the multiple sequential signal packets is not truncated or lost bypremature termination of those signals. At the termination of suchmultiple upstream signal packets, the signal power no longer exceeds thethreshold signal 114, and the switches 104 and 130 immediately assumetheir normal positions, thereby preventing any ingress noise fromentering the CATV network 20 after the longer or multiple sequentialvalid upstream packets have been transmitted.

The situation just described is illustrated by the waveform diagramsshown in FIG. 5, taken in conjunction with FIG. 3. The signal 106represents three, for example, sequential valid upstream packets orsignals. The trigger signal 120 assumes the logic high level at timepoint 142 in response to recognizing the first of the sequential validupstream packets. The one-shot timer 122 is triggered and causes theoutput signal 136 to be asserted at time point 142. The control signal126 from the OR gate 124 also assumes a logic high level at time point142 in response to the assertion of the control signal 136. Theelectronic switches 104 and 130 assume their activated positions inresponse to the logic high control signal 126. At time point 140, theone-shot timer 122 times out, causing its output signal 136 to assume alogic low level. However, the instantaneous power level from themultiple sequential upstream signal packets continues to exceed thethreshold power level, until the sequence of multiple upstream signalpackets terminates at time point 146. So long as the signal 120 is at alogic high level, the control signal 126 from the OR gate 124 causes theelectronic switches 104 and 130 to remain in the activated position,conducting the multiple sequential valid upstream signal packets to theCATV network 20. Once the sequence of multiple valid upstream signalpackets has been transmitted, which occurs at time point 146, theabsence of any further valid upstream signal causes the instantaneouspower level to fall below the threshold power level, and the signals 120and 126 assume a logic low level. The electronic switches 104 and 130respond by assuming their normal positions to prevent the furthertransmission of upstream signals to the CATV network.

If the instantaneous power of ingress noise exceeds the threshold powerlevel, the electronic switches 104 and 130 assume their activatedpositions, as can be understood from FIG. 3. An unusually high and shortduration power level of ingress noise can cause this situation. Underthat circumstance, the trigger signal 120 assumes a logic high level,and the one-shot timer 136 is triggered and asserts the output signal136. The electronic switches 104 and 130 assume their activatedpositions, allowing the ingress noise to pass through the upstreamfilters 102 and 134. Until the one-shot timer 122 times out, ingressnoise will be allowed to enter the CATV network 20. The effect of thisingress noise is minimized by the time constant of the one-shot timer122 extending only for the maximum time duration of the longest singlevalid upstream signal packet permitted under the communication protocol.

The response to ingress noise having instantaneous power that exceedsthe threshold is illustrated by the waveform diagrams shown in FIG. 6,taken in connection with FIG. 3. The ingress noise signal is shown at106. Because the instantaneous power of the ingress noise exceeds thethreshold, a logic high trigger signal 120 is asserted from thecomparator 112 at time point 148, thereby triggering the one-shot timer122 and causing the signal 136 to be asserted at the same time point148. The logic high signal 136 causes the OR gate 124 to assert thelogic high control signal 126 at time point 148. The electronic switches104 and 130 assume their activated positions for the duration of thehigh level of the control signal 126. At time point 150, theinstantaneous power from the ingress noise falls below the thresholdpower level, causing the comparator 112 to assert a logic low triggersignal 120. However, the one-shot timer 122 has not timed out andcontinues to deliver the logic high signal 136 for the time duration ofits time constant, until time point 140. The control signal 126 from theOR gate 124 transitions to a logic low level at time point 140 when theone-shot timer 122 times out, causing the electronic switches 104 and130 (FIG. 3) to assume their normal positions. The electronic switch 104connects the termination resistor 103 to terminate any further upstreamsignals to ground and thereby prevent any further transfer of upstreamsignals to the CATV network.

An alternative form 160 of the upstream noise mitigation circuit, shownin FIG. 7, reduces the amount of time that ingress noise may beconducted to the CATV network 20 after the initial instantaneous powerof the ingress noise is sufficient to exceed the threshold power level,compared to the response of the circuit 100 (FIG. 3). The upstream noisemitigation circuit 160 shown in FIG. 7 includes many of the samecomponents as the upstream noise mitigation circuit 100 (FIG. 3), andthose same components function in the manner previously described.

In response to the instantaneous power of the ingress noise exceedingthe threshold power level, represented by signal 114, the comparator 112supplies the logic high trigger signal 120, in the manner previouslydescribed. The logic high trigger signal 120 is applied to a one-shottimer 162, to the input terminal of a SPDT RF electronic switch 164, toa second one-shot timer 168, and to the set terminal of a set-resetlatch 172. In response to the logic high signal 120, the first one-shottimer 162 triggers and supplies an output signal 166. Simultaneously,the second one-shot timer 168 is triggered and supplies a signal 170.The latch 172 is immediately set in response to the logic high triggersignal 120 and supplies the control signal 126 to the RF electronicswitches 104 and 130, causing them to switch to their activatedpositions and establish the upstream signal communication path forconducting upstream signals through the upstream signal filters 102 and134. In this manner, the noise mitigation circuit 160 responds almostinstantaneously to the instantaneous power of the upstream signalexceeding the threshold to immediately conduct the upstream signal tothe CATV network without delay and without the risk of diminishing orlosing some of the information contained in the upstream signal. In thisregard, the upstream noise mitigation circuit 160 (FIG. 7) is similar ininitial response to the upstream noise mitigation circuit 100 (FIG. 3).However, the upstream noise mitigation circuit 160 has the capability ofmore quickly closing the upstream communication path through theswitches 104 and 130 when the upstream communication path was initiallyestablished in response to ingress noise.

The rapid closure of the upstream communication path in response toingress noise is accomplished by integrating the signal 120 for apredetermined time established by the time constant of the one-shottimer 162. The logic high trigger signal 120 represents the power of theingress noise exceeding the predetermined threshold power level.Integrating the logic high trigger signal 120 results in a value whichrepresents energy above the threshold power level for the time durationof integration. Integration occurs over the time that the signal 166 isasserted by the one-shot timer 162. If the amount of power integratedduring this time, i.e. energy, is not sufficient to confirm a validupstream signal with continuous sustained instantaneous power, theswitches 104 and 130 are moved to their normal positions, therebyterminating the upstream communication path. Since ingress noisegenerally does not contain significant sustained energy even though aninitial burst of the ingress noise may have sufficient instantaneouspower to exceed the threshold, the upstream communication path isquickly closed in a typical ingress noise situation.

Integrating the power represented by the threshold power level isaccomplished by an integration circuit 179. The integration circuit 179includes an operational amplifier 176. The positive input terminal ofthe operational amplifier 176 is connected to ground reference. Acapacitor 178 is connected between the negative input terminal and theoutput terminal of the operational amplifier 176. The negative inputterminal of the operational amplifier 176 is the input point for signalsto the integration circuit 179.

Prior to commencement of integration, the switch 164 is in its normalposition shown in FIG. 7. In the normal position of the switch 164, apositive voltage signal 171 is conducted from a power supply source 175to a resistor 174 which is connected to the negative input terminal ofan operational amplifier 176. Applying the positive voltage to thenegative input terminal of the operational amplifier 176 has the effectof causing integration across the capacitor 178 to establish an outputsignal 180 at a voltage level near the ground reference. A voltage levelnear the ground reference constitutes a logic low signal. Thus, in thenormal position of the switch 164, the output signal 180 from theintegrator circuit 179 is at a logic low level.

In response to the control signal 166 moving the switch 164 from itsnormal position shown in FIG. 7 to its activated position which is thealternate of that position shown in FIG. 7, the logic high triggersignal 120 is applied through the resistor 174 to the negative inputterminal of the operational amplifier 176. So long as the trigger signal120 is at the logic high level, the output signal 180 from theoperational amplifier 176 remains at a logic low level. However, becauseingress noise typically has the effect of rapidly subsiding ininstantaneous power, the instantaneous power will usually not exceed thethreshold for a significant sustained amount of time, thereby causingthe signal 120 to assume a logic low level during the time that theone-shot timer 162 supplies the control signal 166. Consequently, withthe switch 164 in the activated position and the signal 120 at a logiclow level, the operational amplifier 176 integrates this change of inputsignal level across the capacitor 178, which causes the output signal180 to start increasing from the ground reference level. If theinstantaneous power of the ingress noise remains low for a significantportion of the time that the one-shot timer 162 asserts the controlsignal 166, as is typical with ingress noise having an initialmomentarily-high instantaneous power burst, the voltage across thecapacitor 178 will increase to a level which corresponds to a logic highlevel of the signal 180.

The logic high output signal 180 is applied to one input terminal of anAND gate 167. The control signal 166 is applied to another inputterminal of the AND gate 167. The input terminal to which the controlsignal 166 is applied is an inverting input terminal, thereby causingthe AND gate 167 to respond to the inverted logic level of the controlsignal 166. The signal 180 remains at a logic high level for a timeperiod after integration ceases from the integration circuit 179, andthe control signal 166 assumes the logic low level at the end of theintegration time established by the one-shot timer 162. At that point,the AND gate 167 responds to two logic high signals (the logic lowsignal 166 is inverted at the input terminal), resulting in a logic highlevel signal 169 applied to an OR gate 182. The OR gate 182 supplies alogic high level signal 184 to a reset terminal of the latch 176. Thelatch 176 resets, and de-asserts the control signal 126 to the switches104 and 130, thereby closing the upstream communication path through theupstream filters 102 and 134. Thus, soon after the initial instantaneouspower of the ingress signal diminishes and the integration time set bythe one-shot timer 162 expires, the upstream communication path isclosed to the further conduction of upstream signals, thereby preventingany further ingress noise from entering the CATV network.

During the time and situation just described, another AND gate 185 hasno effect on the functionality. The signal 170 supplied by the one-shottimer 168 is asserted for a considerably longer period of time than theone-shot timer 162 asserts the control signal 166. The time of assertionof the signal 170 is the length of time, plus a margin for componenttolerances, of the longest single valid upstream packet or signalpermitted under the signal communication protocol. The time ofintegration represented by the assertion of the control signal 166 isconsiderably less than the longest single valid upstream packet. Duringthe integration of the instantaneous power of the ingress noise over thetime duration of the control signal 166, the output signal 170 is at alogic high level, the control signal 126 is at a logic high levelbecause the latch 172 will have been set by the trigger signal 120,before the signal 120 assumes a logic low level after the initial highinstantaneous power of the ingress noise has dissipated. The inputterminals of the AND gate 185 to which the signals 120 and 170 areapplied are inverting. Thus, under these conditions, the AND gate 185supplies an output signal 187 at a logic low level.

The situation of terminating the upstream communication path created bya burst of ingress noise before expiration of the time duration of amaximum-length valid upstream signal or packet is illustrated by thewaveform diagrams shown in FIG. 8, taken in connection with FIG. 7. Theingress noise signal is shown at 106. The instantaneous power of theingress noise exceeds the threshold power level and causes a logic hightrigger signal 120 from the comparator 112 at time point 148, therebytriggering the one-shot timers 162 and 168 and causing the controlsignals 166 and 170 to be asserted at the time point 148. The controlsignal 126 from the latch 172 also assumes a logic high level at timepoint 148 because the logic high trigger signal 120 sets the latch 172.The electronic switches 104 and 130 assume their activated positions forthe duration of the logic high control signal 126 to maintain theupstream communication path. At time point 150, the instantaneous powerof the ingress noise falls below the threshold power level, and thetrigger signal 120 assumes a logic low level. However, the firstone-shot timer 162 has not timed out and continues to deliver thecontrol signal 166 until it times out at time point 188. The timeduration between time points 148 and 188 is the time constant of theone-shot timer 162 which establishes the time duration of integration.The time for integrating a valid upstream signal is the time betweentime points 148 and 188.

If the integrated value indicates an upstream signal of unsustainedinstantaneous power, consistent with ingress noise that rapidlydissipates, the resulting logic high signal 180 from the integrator 179is applied to the OR gate 182. The OR gate 182 supplies the logic highsignal 180 at time point 188 which, when logically AND-ed with thelogical inversion of signal 166, causes the AND gate 167 to assert thesignal 169. The OR gate 182 responds by asserting a logic high signal184, which resets the latch 172, thereby de-asserting the control signal126. The upstream communication path is terminated when the switches 104and 130 assume their normal positions.

As is understood from FIG. 8, the upstream communication path remainsopen from time point 148 to time point 188. This time is considerablyless than the maximum time length of a single valid upstream packet orsignal, represented by the time between points 148 and 189, or betweentime points 148 and 150 (FIG. 6). Consequently, even though the upstreamcommunication path is immediately established to allow upstream signalcommunication whenever the instantaneous power exceeds the threshold,that upstream communication path is closed to further upstreamcommunication very rapidly thereafter if spurious ingress noiseestablished that communication path.

Whenever an upstream signal has sustained instantaneous power, the noisemitigation circuit 160 assures that the upstream signal will beconducted to the CATV network. Such circumstances indicate a validupstream signal. As understood from FIG. 7, the trigger signal 120 isasserted at a logic high level when the valid upstream signal exceedsthe threshold. The latch 172 is set and asserts the logic high controlsignal 126 which moves the switches 104 and 132 their activatedpositions to establish the upstream communication path. The timers 162and 168 are triggered, and the one-shot timer 162 moves the switch 164to its activated position. The output signal 180 remains at a logic lowlevel during the time of a valid upstream signal while the one-shottimer 162 asserts the control signal 166 and while the logic hightrigger signal 120 remains at a logic high level due to the sustainedinstantaneous power of the valid upstream signal exceeding thethreshold. The logic low signal 180 and the inversion of the logic highsignal 166 at the input terminal of the AND gate 167 causes the AND gate167 to assert a logic low signal 169, which has no effect on the OR gate182 or the latch 172. Thus, during the transmission of a valid upstreamsignal, the AND gate 167 has no effect on the status of the latch 172.

On the other hand, the time constant of the one-shot timer 168 isconsiderably longer than the time constant of the one-shot timer 162.The signal 170 from the timer 168 is asserted for the time duration of asingle valid maximum-length upstream packet or signal. The logic highlevel of the signal 170 is inverted at the input terminal of the ANDgate 185. At this time, the control signal 126 is at a logic high levelbecause the latch 172 has been set. The continuous instantaneous powerof the valid upstream signal is represented by a logic high level of thetrigger signal 120. The logic high level of the signal 120 is invertedat the AND gate 185. The logic level of the signals applied to the ANDgate 185 causes it to supply a logic low signal 187, which has no effecton the latch 172 during conditions of sustained instantaneous power fromthe valid upstream signal.

When the valid upstream signal terminates, the logic high level of thesignal 120 changes to a logic low level. The logic low level signal 120is inverted at its input terminal to the AND gate 185. The logic highsignal 170 is still asserted by the one-shot timer 168, because thetimer 168 times the duration of a single valid maximum-length upstreamsignal. Until the one-shot timer 168 de-asserts the signal 170, the ANDgate 185 will not assert a logic high signal 187. However, when thesignal 170 is de-asserted, the AND gate 185 applies the logic highsignal 187 to the OR gate 182. The OR gate 182 asserts the signal 184 toreset the latch 172, and the control signal 126 is de-asserted. Theswitches 104 and 132 move to their normal positions and terminate theupstream communication path through the filters 102 and 134.

In response to sustained instantaneous power representative of a validupstream signal, the noise mitigation circuit 160 assures that anupstream communication path will be established for the maximum timeduration of a single valid upstream signal, provided that there issufficient instantaneous energy in the upstream signal during theintegration time established by the signal 166. In this manner, thecircuit 160 is similar to the circuit 100 (FIG. 3) which assures thatthe upstream communication path remains established for the timeduration of a single valid maximum-length upstream signal or packet.However, unlike the circuit 100 (FIG. 3) the circuit 160 discriminatesbetween short-duration high instantaneous power ingress noise andcontinuous-duration high instantaneous power upstream signals andrapidly terminates the upstream communication path in response to theformer.

The situation of maintaining the upstream communication path in responseto sustained instantaneous energy of an upstream signal during theintegration time established by the time constant of the one-shot timer162, to allow adequate time for a single valid upstream packet ofmaximum duration to be transmitted, is illustrated by the waveformdiagrams shown in FIG. 9, taken in connection with FIG. 7. The upstreamsignal is represented by a packet having a time duration less than themaximum allowed time duration for single valid upstream packet as shownat 106. The instantaneous power of the upstream packet 106 exceeds thethreshold power level and causes a logic high trigger signal 120 fromthe comparator 112 at time point 148, thereby triggering the one-shottimers 162 and 168 and causing the control signals 166 and 170 to beasserted at the same time point 148. The control signal 126 from thelatch 172 also assumes a logic high level at time point 148 due to theassertion of the logic high signal 120. The electronic switches 104 and130 assume their activated positions for the duration of the logic highsignal 126 and establish the upstream communication path. At time point188, the first one-shot timer 162 times out and de-asserts the controlsignal 166. The time duration between time points 148 and 188establishes the time duration of integration.

During the time of integration, the instantaneous power of the singlepacket 106 continuously exceeds the threshold level. Consequently, theoutput signal 180 from the integration circuit 179 remains at a logiclow level, and the inversion of the control signal 166 at the AND gate167 maintains the output signal 169 in a logic low level. At time point188 when the one-shot timer 162 times out, the control signal 166assumes a logic low level, but the inversion of that logic low level atthe input terminal to the AND gate 167, coupled with the continuouslogic low level signal 180 continues to maintain the output signal 169at a logic low level. The logic low signal 169 does not change for theduration of the situation shown in FIG. 9. As a result, the AND gate 167has no effect on resetting the latch 172 in this situation.

During the time between points 148 and 188, the logic high controlsignal 126, the logic high trigger signal 120, which is inverted at itsinput terminal to the AND gate 185, and the logic high control signal170, which is also inverted at its input terminal to the AND gate 185,cause the output signal 187 from the AND gate 185 to remain at a logiclow level. Therefore, during this time between points 148 and 188, thesignal 187 from the AND gate 185 has no effect on resetting the latch172.

At time point 190 the packet 106 terminates. The instantaneous powerassociated with the packet 106 also terminates, causing the triggersignal 120 to achieve a logic low level. However, the one-shot timer 168has not yet timed out, so its output signal 170 remains at a logic highlevel until time point 189. The logic low level trigger signal 120 doesnot change the state of the AND gate 185. Consequently, the latch with172 remains set at time point 190.

When the one-shot timer 168 times out, at point 189, the control signal170 assumes a low logic level. The low logic signal 170 is inverted atits input terminal to the AND gate 185. The trigger signal 120previously assumed a logic low level at time point 190. The inversion ofthe signals 120 and 170 at the input terminals to the AND gate 185results in three logic high input signals to the AND gate 185, causingthe output signal 187 to assume a logic high level. The logic highsignal 187 is applied to the OR gate 182, and the output signal 184 fromthe OR gate resets the latch 172. Upon reset, the latch 172 de-assertsthe control signal 126 at time point 189, thereby closing the upstreamcommunication path through the filters 102 and 134 as a result of theswitches 104 and 130 assuming their normal positions.

Thus, as is understood from FIG. 9, a valid upstream signal of anyduration will exceed the minimum power threshold measured during theintegration time established by the one-shot timer 162, and as aconsequence, the latch 172 will continue to assert the control signal126 and maintain the upstream communication path through the filters 102and 104. The upstream communication path will be maintained for theduration of the time constant of the one-shot timer 168, during whichits output signal 170 is asserted at a logic high level. By maintainingthe upstream communication path during the time that the one-shot timer168 asserts the control signal 170, it is assured that all validupstream signals having a time length at least equal to the maximumlength of a single valid upstream signal will pass through the upstreamcommunication path. Consequently, none of the information contained in asingle valid upstream packet will be lost or truncated.

The upstream signal communication path remains established during thetime between the actual end of the valid upstream packet and the end ofa maximum-length valid upstream packet, represented by the difference intime between points 190 and 189, but that amount of time is relativelyshort and maintenance of the upstream communication path during thistime assures that a valid upstream signal packet of any length up to themaximum length will be transmitted without loss or truncation of any ofits information.

In addition to the previously described advantages of quickly closingthe upstream communication path after it was established by ingressnoise and of establishing the upstream communication path for themaximum length of a valid upstream signal, the noise mitigation circuit160 also has the capability of transmitting multiple sequential validdata packets, without loss or truncation of information. This situationcan be understood by reference to FIG. 10, taken in conjunction withFIG. 7.

The first valid upstream packet of the sequence of multiple validupstream packets, shown at 106 in FIG. 10, establishes the upstreamcommunication path due to its sustained instantaneous energy. Thisenergy is sustained during the integration time established by theone-shot timer 162. The control signal 166 is asserted at a high logiclevel until time point 188, and the control signal 170 is asserted at ahigh logic level until time point 189.

The instantaneous power of the sequence of multiple valid upstreampackets remains above the threshold level and the trigger signal 120remains asserted at a logic high level for the duration of that sequenceof packets until time point 193, when the instantaneous power of themultiple sequential upstream packets terminates. The one-shot timer 168does not time out until time point 189, at which point its output signal170 assumes a logic low level at time point 189. The low logic level ofthe control signal 170 is inverted at its input terminal to the AND gate185. However, at time point 189, the states of the input signals to theAND gate 185 result in the AND gate 185 supplying a logic low outputsignal 187. The logic low output signal 187 has no effect on the OR gate182 and the latch 172 remains set.

At time point 193, the instantaneous power of the sequence of multiplevalid upstream packets 106 falls below the threshold, causing thetrigger signal 120 to assume a logic low level. The logic low level ofthe signal 120 at time point 193 is inverted at its input terminal tothe AND gate 185, causing the AND gate to assert a logic high outputsignal 187. The logic high signal 187 causes the OR gate 182 to assertthe signal 184, thereby resetting the latch 172 and de-asserting thesignal 126. The switches 104 and 130 assume their normal positions,thereby terminating the communication path through the upstream signalfilters 102 and 134.

In this manner, the upstream communication path is maintained for theduration of the multiple sequential packets, represented by the timebetween points 148 and 193. However, after the last packet in themultiple sequential series of valid upstream packets ends, the upstreamcommunication path is closed to the further transmission of upstreamsignals, thereby preventing ingress noise from entering the CATVnetwork.

As has been described in conjunction with FIGS. 7-10, any upstreamsignal, whether a valid upstream signal or ingress noise, which hassufficient instantaneous power to exceed the threshold will immediatelyopen the upstream communication path through the filters 102 and 134. Inthis sense, the noise mitigation circuit 160 does not distinguishbetween a valid upstream signals and invalid ingress noise which mayhave sufficient energy to exceed the threshold. Not distinguishingbetween these signals assures that there is no delay in transmittingvalid upstream signals. A delay in transmitting valid upstream signalscould lose or truncate part of the information contained in those validsignals. However, once the upstream communication path has beenestablished, the sustained instantaneous power of the upstream signal isintegrated during the integration time established by the one-shot timer162, between time points 148 and 188. If the instantaneous power of theupstream signal is not sustained, as is the typical case with ingressnoise, the upstream communication path is terminated thereafter at timepoint 188.

On the other hand, if the instantaneous power of the upstream signal issustained during the integration time, as may be the case with a validupstream signal of any duration, the upstream communication path ismaintained for the maximum duration of a single valid upstream signal orpacket, represented by the time between points 148 and 189. In thismanner, an upstream communication path is assured for the time durationnecessary to transmit a single valid upstream packet of maximum timeduration established by the communication protocol. Again, no loss ortruncation of information of any valid upstream packet is assured.Similarly, there is no loss or truncation of the information containedin a sequence of multiple valid upstream packets, even when the multiplesequential upstream packets have a time duration which exceeds themaximum time duration of a single valid upstream packet. The upstreamcommunication path remains open for the duration of the multiplesequential upstream packets, represented by the time between points 148and 193. However as soon as the instantaneous power represented by themultiple upstream sequential packets falls below the threshold, at timepoint 193, the upstream communication path is terminated to prevent anyingress noise from entering the CATV network at the conclusion of themultiple sequential upstream packets.

Now referring to FIG. 11, the CATV network interface device 10 mayinclude a bypass circuit 200 to create a passive closed circuit duringpower loss conditions where the noise mitigation circuit 100, 160,having active circuitry, may create an open. The bypass circuit 200provides for continuous and reliable use in emergency and criticalcircumstances, also known as lifeline preservation. During power lossconditions, use of cable modems, VoIP adapters, and E-MTAs may beunavailable where transmission of signal must pass through activecircuitry. A bypass circuit 200 switches the signal path to pass onlythrough passive circuitry.

With continued reference to the figures, FIG. 12 illustrates oneembodiment of the bypass circuit 200 as it may be integrated within aCATV network interface device 10. The bypass circuit 200 may include anelectro-mechanical double-pole double-throw (EM DPDT) relay 210. The EMDPDT relay 210 switches between two signal paths, the noise mitigationpath 204 and the lifeline path 202. The noise mitigation path 204 isdescribed in detail with reference to FIGS. 1-10. The lifeline path 202bypasses the noise mitigation path 204 to exclude active circuitry fromthe signal path, whether downstream signals 74 or upstream signals 80.

The EM DPDT relay 210 includes a control circuit 212. The controlcircuit 212 switches the signal paths between the lifeline path 202 andthe noise mitigation path 204 depending on whether the EM DPDT relay 210is energized or de-energized. For example, during power off conditions,the EM DPDT relay 210 is in the de-energized state, so the controlcircuit 212 switches the signal path to the lifeline path 202, as shownin FIG. 12. During the energized state, when power is on, the controlcircuit 212 switches the signal path to the noise mitigation path 204.

In the illustrated embodiment, the EM DPDT relay 210 is an 8-pin relay.The 8-pins are arranged in such a way that during the power-offcondition, pins 2, 3, 6, and 7 have continuity, activating the lifelinepath 202. In the power-on condition, pins 3, 4, 5, and 6 havecontinuity, activating the noise mitigation path 204.

The benefit of the termination resistors 103 and 190 is their ability toavoid signal reflections, as understood from FIGS. 3 and 7. Theproclivity for high-frequency signals to reflect is related to theimpedance characteristic of the termination of the conductor whichconducts those signals and to the frequency of those signals, as is wellknown. For this reason, coaxial cables are typically terminated byconnecting a terminating impedance between the signal-carrying centerconductor and the surrounding reference plane shielding. The terminatingimpedance value should have a value equal to a characteristic impedancebetween the signal-carrying conductor and the reference plane shielding,to minimize signal reflections.

The values of the termination resistors 103 and 190 are selected toequal the characteristic impedance of the coaxial cables which form thedrop cables 38 (FIG. 2), and that value is typically 75 ohms. Matchingthe value of the termination resistors 103 and 190 to the characteristicimpedance of the coaxial cables minimizes the amount of signalreflection. Reflected signals combine with the incident downstreamsignals and cancel or degrade the downstream signals. Minimizing thesignal reflection maximizes the quality and fidelity of the downstreamsignals and enhances the quality of service provided from the CATVnetwork.

A further feature is the incorporation of a gas tube surge protectiondevice 192 in the network interface device 10, as shown in FIG. 3. Thegas tube surge protection device 192 (FIG. 3) is an integral componentand is permanently enclosed within the housing 12 (FIG. 1). The gas tubesurge protection device 192 provides protection against destruction ofand damage to the components of the interface device 10 which typicallymight arise from lightning strikes to the CATV network 20 or from otherunanticipated high voltage and high current applications to the CATVnetwork. Because the infrastructure of the CATV network extends over aconsiderable geographical area, a lightning strike or other unexpectedhigh voltage, high current application may adversely affect or destroyelectronic components in the CATV network infrastructure, including theinterface devices 10. For this reason, industry standards recommend someform of surge protection.

The typical previous types of surge protectors are inductor-capacitorcircuits, metal oxide varistors, and avalanche diodes. These devices maybe made a part of a network interface device, or these devices areincluded in cable taps 36 (FIG. 2). Inductor-capacitor circuits, metaloxide varistors and avalanche diodes only offer effective protectionagainst relatively lower voltage and lower current surges.Inductor-capacitor circuits, metal oxide varistors and avalanche diodesare susceptible to failure in response to higher voltage and highercurrent surges, such as those arising from lightning strikes. Of course,the failure of such devices eliminates any protection and usually leadsto failure of the components within the CATV network and within thenetwork interface device. The CATV service provider may replace failednetwork interface devices, but a failed surge protector may not berecognized until after the destruction of other components has occurred.

Grounding blocks are another previous form of surge protection.Grounding blocks are devices used in cable taps 36 (FIG. 2), and includeconductors which provide a common ground reference among the variousdevices within the cable taps 36. Grounding blocks may also be used inconnection with a gas tube surge protection device within the cable taps36, but gas tube surge protection devices are not commonly used withgrounding blocks because of the relative expense associated with suchdevices and the perceived satisfactory protection available from thecommon grounding connection. Another disadvantage of using a gas tubesurge protection device with a grounding block is that the arrangementis not fully effective. The gas tube surge protection device may belocated at the cable taps 36 (FIG. 2), but the cable taps 36 areseparated by drop cables 38 from the network interface devices 10. Alightning strike or other surge condition unexpectedly applied to one ofthe drop cables 38 will be conducted directly to the interface device 10which may have no surge protection, as well as to the cable tap 36. Anyprotection provided by the grounding block, whether or not it includes agas tube surge protection device, is assuredly not available to thenetwork interface device 10, because the adverse surge can be conducteddirectly to the network interface device 10 and avoid the gas tube surgeprotection device in the cable tap 36.

Incorporating the gas tube surge protection device 192 in the networkinterface device 10, as shown in FIG. 3, offers a greater capability toprotect against higher voltage and higher current surges and againstrepeated surges. The gas tube surge protection device 192 remainsfunctional in response to higher voltage and higher current surges thancan be responded to by inductor-capacitor circuits, metal oxidevaristors and avalanche diodes. The gas tube surge protection device 192also offers a capability to resist a greater number of multiple surgescompared to other known previous devices. While the previous devices mayrespond to a moderate number of moderate level surges, the number ofsuch responses is limited. After that number is exceeded, such previousdevices tend to fail even in response to moderate surge conditions.

Locating the gas tube surge protection device 192 in the networkinterface device 10 provides the best level of protection against highvoltage and high current surges arising within the CATV networkinfrastructure and arising from active and passive subscriber equipmentconnected to the network interface device 10. Downstream surges will besuppressed as they enter the network interface device 10 from the CATVnetwork infrastructure. Even though it is unlikely that a surgecondition will originate at the subscriber equipment connected to theinterface device 10, the gas tube surge protection device 192 willprovide protection for the other components within the CATV network 20from upstream surges.

Incorporating the gas tube surge protection device 192 in the networkinterface device 10 also offers economic advantages, which aretranslated into a lower cost to the CATV service provider. The increasedcost arising from incorporating the gas tube surge protection device 192in the network interface device 10 is more than offset by avoiding thenecessity to occasionally replace entire failed network interfacedevices and/or other components within the CATV network infrastructure.

As described above, there are numerous advantages and improvementsavailable from an embodiment. The upstream noise mitigation circuits(100 and 160, FIGS. 3 and 7) respond to the instantaneous power ofupstream signals. When the instantaneous power exceeds a predeterminedthreshold, a signal path for conducting the upstream signal to the CATVnetwork is immediately established. Establishing the upstreamcommunication path immediately when the instantaneous power of theupstream signal exceeds the threshold substantially reduces ordiminishes the risk that information contained in the upstream signalwill be lost, truncated or diminished. The risk of truncating or losinginformation in the upstream signal is considerably reduced or diminishedcompared to devices which integrate the power of the upstream signalover a time period before establishing the upstream communication path.By responding to the instantaneous power, the information in validupstream signals is preserved. On the other hand, the upstream noisemitigation circuits 100 and 160 (FIGS. 3 and 7) offer the capability ofquickly isolating and terminating the upstream communication path andthereby minimizing the ingress noise entering the CATV network.

In addition, the incorporation of the gas tube surge protection devicewithin the network interface device itself offers substantial protectiveand economic advantages over the previous known uses of surge protectiondevices for CATV networks.

Part II

FIG. 13 depicts a block diagram of an embodiment of basic functionalcomponents within a network interface device or NID 1300. An input 1310receives a signal which is sent to active device(s) 1350 via the activebranch circuit 1330 or to passive device(s) 1340 via passive branchcircuit 1320. Within the active branch circuit 1330, the noise manager1335 operates to mitigate ingress noise by selectively establishing anupstream path based on the detection and evaluation of upstream signals.

FIG. 14 depicts a block diagram of another embodiment of basicfunctional components within a network interface device or NID 1400. Theactive branch circuit 1430 is controlled by or coupled to a separatenoise manager 1435.

In one embodiment, each of the noise managers or noise managementdevices 1335 and 1435 is a low loss, broadband CATV/MoCA compatible,noise mitigation device. The NID having the noise manager may be usednearly anywhere in the home cable network, for example, it may beinstalled at the entry point of the home for the CATV signals. The noisemanager mitigates (for example, by blocking) the in-band noise of thereturn (upstream) communication path when there is no active or validcommunication transmitting. This noise reduction (such as, by isolation)translates to significantly greater nodal network signal to noise ratios(SNR). Additionally, the higher SNR may lead to a reduction in thetransmitted power requirement at the Cable Modem which further reducescircuit nonlinearities such as; harmonics, beats, and spurs generated bynonlinear passives and actives in the network path. The result is anoverall quality improvement for the end users as well as a reduction inmaintenance or repair service calls.

Additionally, the use of a power loss bypass circuit with the noisemanager 1335 or 1435 may be employed on the active branches of networkinterface devices where some means of power loss or return losspreservation may already be employed. In addition, a bypass may beemployed for the sake of versatility of use so the noise manager 1335 or1435 may instead be employed on the passive VOIP branch. This can beuseful for all-in-one gateway architecture master device ports, whichhave increased needs for noise reduction while continuing the need foruninterrupted VOIP lifeline services.

In one embodiment, an NID, such as NID 1300 or 1400, provides upstreamnoise management or noise mitigation. The NID includes a signal splitterthat is operable to separate a downstream signal into a passive branchsignal and/or an active branch signal. An active branch circuittransmits the active branch signal to an active subscriber device. Anactive branch circuit noise manager detects an upstream signaltransmitted from the least one active subscriber device and establishesa signal path for the detected upstream signal through the active branchcircuit. The NID also includes a passive branch circuit to transmit thepassive branch signal to a passive subscriber device.

In a further embodiment of the NID above, the active branch circuitnoise manager detects an instantaneous power of the upstream signal and,based on the detection, establishes the signal path for the detectedupstream signal through the active branch circuit. The active branchcircuit noise manager can determine whether the instantaneous power ofthe upstream signal exceeds a threshold limit, and, in response to thedetermination, establish the signal path for the detected upstreamsignal through the active branch circuit. The active branch circuitnoise manager may also determine whether an integration of theinstantaneous power indicates that the upstream signal is ofunsustained, fleeting power; and based on the determination, terminatethe signal path for the detected upstream signal through the activebranch circuit.

In another embodiment of any one of the NIDs above, the NID includes aswitch that controls transmission of the downstream signal to the activesubscriber device. The switch can selectively either enable atransmission of the downstream signal to the active subscriber device orblock the transmission of the downstream signal to the active subscriberdevice. The switch has a signal flow mode and a signal block mode. Theswitch enables transmission between a CATV network and the activesubscriber device when in the signal flow mode and prevents thetransmission between the CATV network and the active subscriber devicewhen in the signal block mode. The switch assumes the signal flow modein response to a normal operation condition and assumes the signal blockmode in response to a power-off condition. The switch may also maintainthe signal flow mode during the normal operation condition.

In a further embodiment of any one of the NIDs above, the active branchcircuit noise manager includes an upstream noise mitigation circuit thatmitigates ingress noise by enabling the signal path only for theupstream signals which have a power content that exceeds a predeterminedthreshold power level.

In another embodiment of any one of the NIDs above, the active branchcircuit noise manager maintains the signal path until a designatedcondition is detected; and blocks the signal path after a designatedcondition is detected. The designated condition may be a predeterminedamount of time. The predetermined amount of time is based on an amountof time to transmit a single valid upstream signal packet of a maximumtime duration permitted by a signaling protocol. The designatedcondition may also be based on an integration of the instantaneous powerof a detected signal.

In a further embodiment of any one of the NIDs above, the active branchcircuit includes the active branch circuit noise manager. Anotherembodiment is an NID that provides upstream noise mitigation. The NIDincludes a signal splitter that separates a downstream signal into apassive branch signal and/or an active branch signal. An active branchcircuit transmits the active branch signal to/from an active subscriberdevice. An active branch circuit noise manager detects an upstreamsignal transmitted from the least one active subscriber device andestablishes a signal path for the detected upstream signal through theactive branch circuit. A passive branch circuit transmits the passivebranch signal to/from passive subscriber device. The NID also includes aswitch (or bypass relay) operable to control transmission of signalsto/from the active subscriber device.

In a further embodiment of the NID above, the switch selectivelyestablishes a connection with the active subscriber device and bypassesthe connection with the active subscriber device. The switch has asignal flow mode and a signal block mode. In the signal flow mode theswitch establishes the connection with the active subscriber device. Inthe signal block mode the switch prevents the connection with the activesubscriber device (for example, by bypassing the active subscriberdevice). The switch assumes the signal flow mode in response to a normaloperation condition, and assumes the signal block mode in response to apower-off condition.

In another embodiment of any one of the NIDs above, the active branchcircuit noise manager detects an instantaneous power of the upstreamsignal and, based on the detection, establishes the signal path for thedetected upstream signal through the active branch circuit.

A further embodiment is an NID that provides upstream noise mitigation.The NID includes an input port used to communicate with a CATV network.A signal splitter separates a downstream signal into a passive branchsignal and/or an active branch signal. The NID includes a gas tube surgeprotector located on a connection between the input port and the signalsplitter. An active branch circuit transmits the active branch signalto/from an active subscriber device. An active branch circuit noisemanager (or noise mitigation circuit) detects an upstream signaltransmitted from the least one active subscriber device and establishesa signal path for the detected upstream signal through the active branchcircuit. A passive branch circuit transmits the passive branch signalto/from passive subscriber device. A bypass circuit bypasses the signalpath through the active branch circuit during a power-off condition.

In another embodiment of the NID above, the active branch circuit noisemanager detects an instantaneous power of the upstream signal and, basedon the detection, establishes the signal path for the detected upstreamsignal through the active branch circuit.

In a further embodiment of any one of the NIDs above, the active branchcircuit noise manager, in response to establishing the signal path forthe detected upstream signal, maintains the signal path for the detectedupstream signal for a predetermined amount of time based on an amount oftime to transmit a single valid upstream signal packet of a maximum timeduration permitted by a signaling protocol.

Another embodiment includes a noise mitigation or noise managementcircuit that reduces or manages ingress noise. The noise managementcircuit detects an upstream signal transmitted from an active subscriberdevice and establishes a signal path for the detected upstream signalthrough the active branch circuit.

In a further embodiment of an instantaneous power of the upstream signaland, based on the detection, establishes the signal path for thedetected upstream signal through the active branch circuit. The noisemanager or noise management circuit can determine whether theinstantaneous power of the upstream signal exceeds a threshold limit,and, in response to the determination, establish the signal path for thedetected upstream signal through the active branch circuit. The noisemanager or noise management circuit may also determine whether anintegration of the instantaneous power indicates that the upstreamsignal is of unsustained, fleeting power; and based on thedetermination, terminate the signal path for the detected upstreamsignal through the active branch circuit.

In another embodiment of any one of the noise mitigation circuits ornoise management circuits above, the noise management circuit mitigatesingress noise by enabling the signal path only for the upstream signalswhich have a power content that exceeds a predetermined threshold powerlevel. Upstream signals which have a power content that does not exceeda predetermined threshold power level are sent to ground through atermination resistor.

In a further embodiment of any one of noise mitigation or managementcircuits above, the noise management circuit maintains the signal pathuntil a designated condition is detected; and blocks the signal pathafter a designated condition is detected. The designated condition maybe a predetermined amount of time. The predetermined amount of time isbased on an amount of time to transmit a single valid upstream signalpacket of a maximum time duration permitted by a signaling protocol. Thedesignated condition may also be based on an integration of theinstantaneous power of a detected signal.

Additional embodiments include any one of the embodiments describedabove, where one or more of its components, functionalities orstructures is interchanged with, replaced by or augmented by one or moreof the components, functionalities or structures of a differentembodiment described above.

It should be understood that various changes and modifications to theembodiments described herein will be apparent to those skilled in theart. Such changes and modifications can be made without departing fromthe spirit and scope of the present disclosure and without diminishingits intended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

Although several embodiments of the disclosure have been disclosed inthe foregoing specification, it is understood by those skilled in theart that many modifications and other embodiments of the disclosure willcome to mind to which the disclosure pertains, having the benefit of theteaching presented in the foregoing description and associated drawings.It is thus understood that the disclosure is not limited to the specificembodiments disclosed herein above, and that many modifications andother embodiments are intended to be included within the scope of theappended claims. Moreover, although specific terms are employed herein,as well as in the claims which follow, they are used only in a genericand descriptive sense, and not for the purposes of limiting the presentdisclosure, nor the claims which follow.

The following is claimed:
 1. A network interface device comprising: asignal splitter configured to separate a downstream signal into one of:(a) a passive branch signal and (b) an active branch signal; an activebranch circuit, wherein the active branch signal is transmittablethrough the active branch circuit to at least one active subscriberdevice; an active branch circuit noise manager configured to: (a) detectan upstream signal transmitted from the least one active subscriberdevice and (b) establish a signal path for the detected upstream signalthrough the active branch circuit; a passive branch circuit, wherein thepassive branch signal is transmittable through the passive branchcircuit to at least one passive subscriber device; and a bypass circuitconfigured to: in response to the active branch circuit noise managerbeing unpowered, switch the active branch signal to a bypass signal paththat bypasses at least the active branch circuit noise manager so as toprevent the active branch signal from being transmitted to the activebranch circuit noise manager, and in response to the active branchcircuit noise manager being powered, switch the active branch signal toan active signal path to the active branch circuit noise manager so asto allow the active branch signal to be transmitted to the active branchcircuit noise manager.
 2. The network interface device of claim 1,wherein the active branch circuit noise manager is configured to detectan instantaneous power of the upstream signal and, based on thedetection, to establish the signal path for the detected upstream signalthrough the active branch circuit.
 3. The network interface device ofclaim 2, wherein the active branch circuit noise manager is furtherconfigured to determine whether the instantaneous power of the upstreamsignal exceeds a threshold limit, and, in response to the determination,switch the signal path for the detected upstream signal to be throughthe active branch circuit.
 4. The network interface device of claim 2,wherein the active branch circuit noise manager is further configuredto: (a) determine whether an integration of the instantaneous powerindicates that the upstream signal is of unsustained, instantaneouspower; and (b) based on the determination; terminate the signal path forthe detected upstream signal through the active branch circuit.
 5. Thenetwork interface device of claim 1, further comprising a switchconfigured to control transmission of the downstream signal to the atleast one active subscriber device.
 6. The network interface device ofclaim 5, wherein the switch is configured to selectively (a) enable atransmission of the downstream signal to the at least one activesubscriber device and (b) block the transmission of the downstreamsignal to the at least one active subscriber device.
 7. The networkinterface device of claim 6, wherein the switch has a signal flow modeand a signal block mode, the switch configured to (a) enabletransmission between a CATV network and the at least one activesubscriber device when in the signal flow mode and (b) prevent thetransmission between the CATV network and the at least one activesubscriber device when in the signal block mode.
 8. The networkinterface device of claim 7, wherein the switch is configured to (a)assume the signal flow mode in response to a normal operation conditionand (b) assume the signal block mode in response to a power-offcondition.
 9. The network interface device of claim 8, wherein theswitch is further configured to maintain the signal flow mode during thenormal operation condition.
 10. The network interface device of claim 1,where the active branch circuit noise manager comprises an upstreamnoise management circuit configured to mitigate ingress noise byenabling the signal path only for the upstream signals which have apower content that exceeds a predetermined threshold power level. 11.The network interface device of claim 1, wherein the active branchcircuit noise manager is configured to: (a) maintain the signal pathuntil a designated condition is detected; and (b) block the signal pathafter the designated condition is detected.
 12. The network interfacedevice of claim 11, wherein the designated condition comprises apredetermined amount of time, the predetermined amount of time based onan amount of time to transmit a single valid upstream signal packet of amaximum time duration permitted by a signaling protocol.
 13. The networkinterface device of claim 1, wherein the active branch circuit comprisesthe active branch circuit noise manager.
 14. A network interface devicecomprising: a signal splitter configured to separate a downstream signalinto one of: (a) a passive branch signal and (b) an active branchsignal; an active branch circuit, wherein the active branch signal istransmittable through the active branch circuit to at least one activesubscriber device and (b) transmittable through the active branchcircuit from the at least one active subscriber device; an active branchcircuit noise manager configured to: (a) detect an upstream signaltransmitted from the least one active subscriber device and (b)establish a signal path for the detected upstream signal through theactive branch circuit; a passive branch circuit, wherein the passivebranch signal is one of: (a) transmittable through the passive branchcircuit to at least one passive subscriber device and (b) transmittablethrough the passive branch circuit from the at least one passivesubscriber device; a switch configured to control transmission of: (a)the downstream signal to the at least one active subscriber device and(b) the upstream signal from the at least one active subscriber device,wherein the switch is configured to selectively (a) establish aconnection with the at least one active subscriber device and (b) bypassthe connection with the at least one active subscriber device; and abypass circuit configured to: in response to the active branch circuitnoise manager being unpowered, switch the active branch signal to abypass signal path that bypasses at least the active branch circuitnoise manager so as to prevent the active branch signal from beingtransmitted to the active branch circuit noise manager, and in responseto the active branch circuit noise manager being powered, switch theactive branch signal to an active signal path to the active branchcircuit noise manager so as to allow the active branch signal to betransmitted to the active branch circuit noise manager.
 15. The networkinterface device of claim 14, wherein the switch has a signal flow modeand a signal block mode, the switch configured to (a) establish theconnection with the at least one active subscriber device when in thesignal flow mode and (b) prevent the connection with the at least oneactive subscriber device when in the signal block mode, wherein theswitch is configured to (a) assume the signal flow mode in response to anormal operation condition, and (b) assume the signal block mode inresponse to a power-off condition.
 16. The network interface device ofclaim 14, wherein the active branch circuit noise manager is configuredto detect an instantaneous power of the upstream signal and, based onthe detection, to establish the signal path for the detected upstreamsignal through the active branch circuit.
 17. A network interface devicecomprising: an input port operable to communicate with a CATV network; asignal splitter operable to separate a downstream signal into one of:(a) a passive branch signal and (b) an active branch signal; a gas tubesurge protector located on a connection between the input port and thesignal splitter; an active branch circuit, wherein the active branchsignal is transmittable through the active branch circuit to at leastone active subscriber device and (b) transmittable through the activebranch circuit from the at least one active subscriber device; an activebranch circuit noise manager operable to: (a) detect an upstream signaltransmitted from the least one active subscriber device and (b)establish a signal path for the detected upstream signal through theactive branch circuit; a passive branch circuit, wherein the passivebranch signal is one of: (a) transmittable through the passive branchcircuit to at least one passive subscriber device and (b) transmittablethrough the passive branch circuit from the at least one passivesubscriber device; and a bypass circuit configured to: in response tothe active branch circuit noise manager being unpowered, switch theactive branch signal to a bypass signal path that bypasses at least theactive branch circuit noise manager so as to prevent the active branchsignal from being transmitted to the active branch circuit noisemanager, and in response to the active branch circuit noise managerbeing powered, switch the active branch signal to an active signal pathto the active branch circuit noise manager so as to allow the activebranch signal to be transmitted to the active branch circuit noisemanager.
 18. The network interface device of claim 17, wherein theactive branch circuit noise manager is operable to detect aninstantaneous power of the upstream signal and, based on the detection,to establish the signal path for the detected upstream signal throughthe active branch circuit.
 19. The network interface device of claim 17,wherein the active branch circuit noise manager is operable to, inresponse to establishing the signal path for the detected upstreamsignal, maintain the signal path for the detected upstream signal for apredetermined amount of time based on an amount of time to transmit asingle valid upstream signal packet of a maximum time duration permittedby a signaling protocol.
 20. The network interface device of claim 1,wherein the active branch circuit noise manager is located in a separateenclosure.
 21. A network interface device comprising: an active branchcircuit, wherein an active branch signal is transmittable through theactive branch circuit to at least one active subscriber device; anactive branch circuit noise manager configured to: (a) detect anupstream signal transmitted from the least one active subscriber deviceand (b) establish a signal path for the detected upstream signal throughthe active branch circuit; and a bypass circuit configured to: inresponse to the active branch circuit noise manager being unpowered,switch the active branch signal to a bypass signal path that bypasses atleast the active branch circuit noise manager so as to prevent theactive branch signal from being transmitted to the active branch circuitnoise manager, and in response to the active branch circuit noisemanager being powered, switch the active branch signal to an activesignal path to the active branch circuit noise manager so as to allowthe active branch signal to be transmitted to the active branch circuitnoise manager.
 22. The network interface device of claim 21, wherein theactive branch circuit noise manager is configured to detect aninstantaneous power of the upstream signal and, based on the detection,to establish the signal path for the upstream signal through the activebranch circuit.
 23. The network interface device of claim 22, whereinthe active branch circuit noise manager is further configured todetermine whether the instantaneous power of the upstream signal exceedsa threshold limit, and, in response to the determination, switch thesignal path for the upstream signal to be through the active branchcircuit.
 24. The network interface device of claim 22, wherein theactive branch circuit noise manager is further configured to determinewhether an integration of the instantaneous power indicates that theupstream signal is of unsustained, instantaneous power; and based on thedetermination; terminate the signal path for the upstream signal throughthe active branch circuit.
 25. The network interface device of claim 22,further comprising a switch configured to control transmission of adownstream signal to the at least one active subscriber device.
 26. Thenetwork interface device of claim 25, wherein the switch is configuredto selectively enable a transmission of the downstream signal to the atleast one active subscriber device and block the transmission of thedownstream signal to the at least one active subscriber device.
 27. Thenetwork interface device of claim 26, wherein the switch has a signalflow mode and a signal block mode, the switch configured to enabletransmission between a CATV network and the at least one activesubscriber device when in the signal flow mode and prevent thetransmission between the CATV network and the at least one activesubscriber device when in the signal block mode.
 28. The networkinterface device of claim 27, wherein the switch is configured to assumethe signal flow mode in response to a normal operation condition andassume the signal block mode in response to a power-off condition. 29.The network interface device of claim 28, wherein the switch is furtherconfigured to maintain the signal flow mode during the normal operationcondition.
 30. The network interface device of claim 21, where theactive branch circuit noise manager is configured to mitigate ingressnoise by enabling the signal path only for the upstream signals whichhave a power content that exceeds a predetermined threshold power level.31. The network interface device of claim 21, wherein the active branchcircuit noise manager is configured to maintain the signal path until adesignated condition is detected and block the signal path after thedesignated condition is detected.
 32. The network interface device ofclaim 31, wherein the designated condition comprises a predeterminedamount of time, the predetermined amount of time based on an amount oftime to transmit a single valid upstream signal packet of a maximum timeduration permitted by a signaling protocol.
 33. The network interfacedevice of claim 21, wherein the active branch circuit comprises theactive branch circuit noise manager.
 34. The network interface device ofclaim 21, wherein the active branch circuit noise manager is located ina separate enclosure.
 35. A network interface device comprising: anactive branch circuit configured to transmit an active branch signal toan active subscriber device; a noise controller configured to controltransmission of an upstream signal from the active subscriber devicethrough the active branch circuit; and a bypass circuit configured toswitch the active branch signal to a bypass signal path when the noisecontroller is not powered so as to prevent the active branch signal frombeing transmitted to the noise controller when the noise controller isnot powered, and wherein the bypass circuit is configured to switch theactive branch signal to an active signal path through the noisecontroller when the noise controller is powered.
 36. The networkinterface device of claim 35, wherein the noise controller is configuredto detect an instantaneous power of the upstream signal and, based onthe detection, to establish a signal path for the upstream signalthrough the active branch circuit.
 37. The network interface device ofclaim 36, wherein the noise controller is further configured todetermine whether the instantaneous power of the upstream signal exceedsa threshold limit, and, in response to the determination, switch thesignal path for the upstream signal to be through the active branchcircuit.
 38. The network interface device of claim 36, wherein the noisecontroller is further configured to determine whether an integration ofthe instantaneous power indicates that the upstream signal is ofunsustained, instantaneous power; and based on the determination;terminate the signal path for the upstream signal through the activebranch circuit.
 39. The network interface device of claim 35, furthercomprising a switch configured to control transmission of a downstreamsignal to the active subscriber device.
 40. The network interface deviceof claim 35, where the noise controller is configured to mitigateingress noise by enabling the signal path only for the upstream signalswhich have a power content that exceeds a predetermined threshold powerlevel.
 41. The network interface device of claim 35, wherein the noisecontroller is configured to maintain the signal path until a designatedcondition is detected and block the signal path after the designatedcondition is detected.
 42. The network interface device of claim 41,wherein the designated condition comprises a predetermined amount oftime, the predetermined amount of time based on an amount of time totransmit a single valid upstream signal packet of a maximum timeduration permitted by a signaling protocol.
 43. The network interfacedevice of claim 35, wherein the noise controller is located in aseparate enclosure.